A blood pressure table or chart shows the systolic and diastolic blood pressure ranges for different categories. These categories are the normal, prehypertension, hypertension stage 1, hypertension stage 2 and hypertensive crisis, according to the AHA.
A blood pressure reading consists of two numbers expressed as a ratio in millimeters of mercury, notes the AHA. The upper number represents systolic pressure, the pressure in the arteries when the heart muscle contracts. The bottom number is the diastolic pressure, representing the pressure in the arteries between heart beats.
The normal blood pressure for a person aged 20 and above is less than 120/80 millimeters of mercury, commonly written as mm Hg, according to the AHA. The prehypertension category represents a blood pressure ranging between 120-139 systolic or 80-89 diastolic. A systolic blood pressure reading between 140 and 159 or a diastolic blood pressure reading between 90 and 99 indicates the first stage of hypertension. A systolic reading of 160 or higher or a diastolic reading of 100 or higher is an indication of hypertension stage 2.
Systolic and diastolic values above 180 or 110 respectively indicate a hypertensive crisis that calls for emergency care. For an individual whose upper and lower blood pressure readings fall in different categories, the higher category indicates the correct blood pressure, notes the Mayo Clinic.